Strip-filter mechanisms in which a strip-like filter material is used as separating medium are disclosed, for example, in DE 43 11 297 A1 or DE 93 01.154 U1. In the operation of such mechanisms, the filter material is advanced as a function of the extent of fouling of the respective strip area through which the filter material flows so as to make fresh filter material available for the filtration process as required. Since the differential pressure between the fouled side and the clean side of the strip-filter mechanism grows with increase in the extent of fouling of the filter material, the value of this differential pressure or the level of the pressure prevailing in the space containing the fluid to be filtered may serve as a criterion for initiation of a filter material feed movement.
The advance of the strip-like filter material may be effected by conventional means by winding the filter material. As is shown, for example, in German Patent Application 101 26 443.7, not of the state of the art, a fouled strip from a roll containing the supply of filter material is subsequently rolled onto a roll connected to the drive shaft of the drive device. In such strip-filter mechanisms, the fluid to be filtered flows from the exterior inward through the unused filter material, so that fouling of the filter material always occurs during the filtration process on the outermost layers of the roll. The outermost layers of the roll are wound from the feed roll when the degree of fouling is sufficiently great, and onto the roll connected to the drive shaft of the drive device.
The electromotive drive devices usually provided for generation of the feed movement by rotation of the corresponding winding shaft result in relatively high structural complexity and correspondingly high costs.